1. Field of the Invention
The invention relates to an isolation cell, and more particularly to an isolation cell using an independent power source.
2. Description of the Related Art
A circuit often includes a plurality of power domains, wherein each power domain may operate in different power voltage modes. For example, there may be one power domain operated in a power voltage-down mode (e.g. no supply of power voltage), while the other power domains are operated in a power voltage-on mode. This can help reduce power consumption. However, a power domain in a power voltage-down mode may provide an input to the power domains in a power voltage-on mode, wherein the input from the power voltage-down power domain may be in an unknown state, which would cause the power domains in the power voltage-on mode to operate abnormally. Therefore, an isolation cell capable of controlling an unknown signal from a power voltage-down power domain to be at a predetermined state is desired.